Want to race in 6 weeks- help!

I have a couple of Cat 5 Crits coming up end of April that I would like to do but I am concerned that my fitness is not even close. I'm not looking to win, all I want to do is not get shot off the back. I've raced several times each of the last couple of years so I do have some experience. I have been riding about 5 hrs/week since Jan, mostly base with some hill repeats tossed in.

What kind of workout schedule would best prepare me for these races assuming I have 5 hrs/week for training? Or is it foolish to think I can race on that little training?

Crank up the intensity. You can do well in a Cat 5 crit with 5 hours of training if it's focused. Get good intensity, and good recovery. Remember that fitness is only part of the equation, so you might want to work on cornering, and if you can get a partner, bump drills on some grass.

Each week, do one workout each of: 15s sprints, 1 minute intervals, and 3 to 5 minute intervals. Do some workouts with full recovery between efforts, and some workouts with little recovery between efforts. That will take 3 of your hours. If you feel ok after those are covered, you can spend your last 2 hours on a TT effort and/or pacelining with friends.